Combination of natural polymer with antimicrobial agents from plants for various applications have attracted many researchers due to its non-toxic properties. In this study, the effects of nano sized Carica papaya (CP) seeds (1% to 5% wt.%) from agro-industrial papaya waste modified biodegradable pullulan on thermal and mechanical properties of the composites were investigated. The effect of silane treatment upon nano sized CP seeds for improving adhesion were examined. Mechanical and thermal properties of the nanosized CP modified pullulan were assessed via tensile test, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Characterization of the film was conducted via Fourier Transform Infrared Spectroscopy (FTIR) and the surface morphology via Field Emission Scanning Electron Microscope (FESEM). Tensile strength and elongation at break of pullulan increase at the expense of Young modulus with increasing CP loading. Silane treatment further increased the tensile strength and Young modulus and slightly decreased the elongation at break. The addition of CP seeds reduced the thermal stability of pullulan. The C-H, O-H, C-O-C, and C=O bond at the peaks of 2925.4 cm-1, 3286.1 cm-1, 1031.7 cm-1, and 1556.3 cm-1, respectively, were confirming the presence of pullulan and CP seeds. Si-O-C and Si-O-Si bonds appeared at the peak 1031.7 cm-1 shows the presence of 3-Aminopropyltrymethoxysilane. Morphological analysis showed that most of the CP seeds at all compositions were bounded well by the pullulan matrix due to silane treatment. Overall, the composition which exhibits an adequate thermal stability and highest tensile strength was silane treated CP modified pullulan at 5% CP content.